The Proposed project goal is to develop and study a DNA vaccine against Respiratory Syncytial Virus (RSV). RSV infects almost all children under two years of age and there is no vaccine available. This project aims to engineer a recombinant DNA vector containing immunologically important regions of the RSV F gene and modified cholera toxin gene. It is expected that the DNA immunogen will induce local and systemic immune response when administered intramuscularly. Since DNA plasmids induce a Th1 cell response, this approach is particularly well suited against RSV where Th1 immune response is very critical in inducing protective immunity. Attractive aspects of the project include the simplicity of the design and development of the DNA plasmid, potential to induce cellular, humoral and the mucosal immune responses. The DNA plasmid will be constructed using a DNA vector (phCMV1 from Gene Therapy Systems) into which regions of RSV F and modified cholera toxin genes will be cloned. The phCMV1 DNA vector contains a CMV promoter, intron A and a strong terminator. DNA will be purified and delivered in mice intramuscularly. Additionally, to test the establishment of Th1 cell response, mice will be immunized with combination of DNA vaccine and recombinant RSV F protein. The humoral and cellular immune responses resulting from immunizations will be analyzed. The ability of the immunogen to protect mice from RSV infection will be evaluated by challenging mice with live RSV. The upper and lower respiratory tract infections will be assessed by studying virus load in upper mucosa and the lungs. This study will lead to an understanding of the DNA vaccination and mucosal immune response and contribute to design and development of a safer and more effective vaccine against RSV and other viruses infecting the mucosa.